1. Technical Field of the Invention
The present application relates to cosmetic or dermatological compositions comprising at least one organic UV screening agent and/or at least one inorganic screening agent, said compositions comprising, formulated into a physiologically acceptable medium, at least the following constituents (A) and (B):
A) a semi-crystalline polymer which is solid at ambient temperature and has a melting point of greater than or equal to 30° C., containing a) a polymeric backbone and b) at least one crystallizable organic side chain and/or one crystallizable organic block forming part of the backbone of the said polymer, the said polymer having a number-average molecular mass Mn of greater than or equal to 1,000, and
B) hollow latex particles having a particle size ranging from 150 to 380 nm.
The present invention also relates to cosmetic applications of the said compositions for topical administration which is useful to protect the skin, lips, nails, hair, scalp, lashes or brows against the deleterious effects of UV radiation, more particularly solar radiation, such compositions comprising at least one organic UV screening agent and/or at least one inorganic UV screening agent, as agents for increasing the sun protection factor (SPF) thereof.
2. Description of Background and/or Related and/or Prior Art
It is known that rays of light with wavelengths of from 280 nm to 400 nm permit tanning of the human epidermis and that, moreover, rays with wavelengths of from 280 nm to 320 nm, which are known under the trademark UV-B, give rise to erythemas and skin burns that can harm the development of a natural tan; this UV-B radiation must therefore be screened out.
It is also known that UV-A rays, with wavelengths of from 320 to 400 nm, which give rise to the tanning of the skin, are capable of inducing impairment thereof, especially in the case of sensitive skin or of skin that is continually exposed to solar radiation. The UV-A rays more particularly give rise to a loss of elasticity in the skin and to the appearance of wrinkles, leading to premature aging. This radiation promotes the onset of the erythemal reaction or amplifies that reaction in certain individuals, and may even be a cause of phototoxic or photoallergic reactions. It is therefore desirable to screen out UV-A radiation as well.
Numerous cosmetic compositions suited for the photoprotection (UV-A and/or UV-B) of the skin have been proposed to date.
These anti-sun compositions are often in the form of an oil-in-water or water-in-oil emulsion, of gels or of non-aqueous products which contain, in various concentrations, one or more insoluble and/or fat-soluble and/or water-soluble, organic and/or inorganic screening agents that are capable of selectively absorbing the harmful UV radiation. These screening agents and their amounts are selected as a function of the desired protection index. Depending on their lipophilic or, alternatively, hydrophilic character, these screening agents may become distributed, respectively, in either the fatty phase or the aqueous phase of the final composition.
For reasons of stability of these compositions and/or of tolerance on the skin, hair or mucosae, it is sometimes difficult to employ large quantities of chemical screening agents and/or mineral screening agents in order to increase the protection index of the suntan compositions. The assignee hereof has therefore sought another means of increasing the protection index of these compositions.
The efficacy of the chemical or physical screening agents is often limited by the problems of dispersal of these screening agents from the cosmetic compositions. A consequence of this is to give rise to heterogeneity in the film which is formed on the surface of the skin, which is detrimental to the quality, stability and efficacy of suntan products.
Proposals have already been made, in U.S. Pat. No. 5,663,213 and EP-1-092,421, EP-1-281,388, EP-1-281,389, EP-1-291,390 and DE10138499, to incorporate hollow latex particles in suntan formulations for the purpose of increasing their protection index.
It has also been proposed, in EP-1-331,000, that a semi-crystalline polymer be included in suntan formulations for the purpose of increasing their protection index.